1. Field of the Invention
The present invention relates to a standing seam roof assembly for a building structure, and more particularly, but not by way of limitation, to a standing seam roof system positionable over a new building structure or over a preexisting roof structure.
2. Discussion of Prior Art
The established method of erecting the roof of a pre-engineered building is to erect the primary structural members; attach the secondary structural members to the primary structural members; secure the appropriate bracing members; roll blanket-type insulation across the secondary structural members; dispose roof panel members over the insulation; and connect the roof panel members to adjacently disposed roof panel members and to the secondary underlying structural members.
Numerous types of roof assemblies have heretofore been proposed for pre-engineered buildings in efforts to provide a watertight roof assembly, while at the same time enabling the roof assembly to expand and contract as changes in temperature are encountered. Typical of such prior art roof assemblies which has met with considerable success in recent years is the standing seam roof assembly. The panel members of the standing seam roof assembly are joined to each other along adjacent sides such that the sides are lapped together to form the standing seams. The panel members of the standing seam roof are secured to the secondary structural members by means of clips. The interconnection of the panel members of the standing seam roof lend stiffness and strength to the roof structure while allowing the roof structure to expand and contact as a function of the coefficient of expansion of the materials of which the roof panels are made and the temperature cycles to which the roof panels are exposed.
The repeated action of expansion and contraction of the panel members of the roof assembly tends to weaken the panel-to-panel lap joints and thus often causes panel separation, structural failure and roof leakage. Leaks are generally caused by the weakening of the fastening members and working or kneading of the sealant disposed at the joints. In many of the prior art roof assemblies, the sealant employed required adhesion, flexibility and water repellency. Further, the design of the joint was in many instances such that the pressure on the sealant varied greatly throughout the length of the side lap and end lap joints of the panels, resulting in uneven distribution and voids of the joint sealant.
Many of the problems discussed hereinabove encountered in prior art standing seam roofs, such as structural failures and leaks, have been overcome by a standing seam floating roof assembly such as is disclosed in copending U.S. patent application Ser. No. 568,083, filed Jan. 4, 1984 by Harold G. Simpson. The standing seam floating roof assembly is formed of elongated metal panels, each of which is provided with a female member formed along one longitudinal edge and a male member formed along the opposed longitudinal edge, adjacently disposed panels being joined by interlocking female and male members thereof to form the standing seam joint. Clips interconnect the standing seam joints and the underlying secondary structure, with the upper portions of the clips hooking over the male members of the panels. Most such clips are of the sliding type which permits the hooking portion to move relative to a supporting base portion connected to the secondary structure, while relative motion between the clip hook and the metal panel is substantially prevented. A sealant material is disposed to form a moisture dam in the interlocking joint of the female and male members.
Panel members of pre-engineered roof systems are constructed of identical sheet metal panels that are laid end to end, as well as side by side as discussed above. This presents the problem of sealing the end or butt joints, especially at the "four corner" areas where four of the panels are interlapped to form a juncture area. Various butt joining techniques have evolved in the prior art, all of which involve selective notching and overlapping to achieve a close fitting juncture area, and liberal application of mastic to effect the best seal possible under the design circumstances. Serious deficiencies have been encountered in prior art butt joints, including water leaks, high costs, tooling complications, packaging, etc.
In addition to the use of standing seam roof assemblies on newly constructed pre-engineered buildings, standing seam roof assemblies are also finding increasing usage in another segment of the roofing industry, that of "built-up roof" replacement. Generally, a built-up roof is formed of a plurality of sections which are interconnected and overcoated with asphaltic composition to provide a watertight seal. While such roof assemblies have generally served successfully, problems have nevertheless been encountered as a built-up roof ages, or when the building settles, or when construction errors result in water standing in pockets on the roof assembly. This standing water often results in deterioration of the roof, causing leaks and the like to occur.
A need has long been recognized for a means for replacing a built-up roof, as well as other conventional roofs, which does not require substantial modification to the preexisting roof and which is economical both in fabrication and on-site construction. Further, it is highly desirable that the new roof assembly be capable of providing a new roof surface independent to the variations in the surface of the preexisting roof assembly. Past repair methods, especially those capable of altering the slope of the roof surface to improve drainage characteristics, have required substantial destruction of the original roof assembly and extensive custom construction, thus exposing the building and its contents to damage by the elements during the reroofing process and being excessively time consuming.